1. Field of the Invention
The present invention relates to the field of circuits for cooling molds, in particular for injection molding parts made of polymer. More precisely, the invention relates to the male portion of a quick coupling for making a temporary junction between a cooling liquid feed hose of such a mold and a duct formed in the mold. The invention also relates to such a quick coupling and to a set of such quick couplings.
2. Brief Description of Related Art
A quick coupling suitable for being used for temporarily connecting a hose to a mold is described in French patent No. 1 556 209. It comprises a female portion and a male portion, with a male plug for insertion in said female portion. Normally, the female portion and the male portion of the quick coupling are secured respectively to the injection mold and to one end of the hose to be connected.
In addition to the male plug, the male portion of the coupling includes locking balls that can be moved between two positions by a locking ring that is slidably mounted on the male plug. In one of those two positions, the balls project outside the ring and can penetrate into an internal groove of the female portion so as to prevent the male and female portions of the coupling being separated. In their other position, the balls are retracted so that the male portion can be engaged in the female portion or separated therefrom.
The coupling can be unlocked by pushing the male plug in the direction for insertion into the female portion, i.e. towards a position in which the male plug is engaged more deeply in the female portion than it is when the coupling is locked. Consequently, while making a coupling, there is a risk that the male plug will be engaged all the way into said position and might remain therein in spite of the action of a return spring urging the locking ring towards a position in which the locking balls project. The hose for connection is flexible, and it is often resiliently curved while being coupled to the mold, and as a result can exert a bias force against the force exerted by the return spring of the ring.
Because of friction against a sealing ring that provides sealing between the male and female portions of the coupling, there is also a risk that the operator will think that the male plug has been pushed far enough into the female portion, even when that is not the case, and the locking balls have not reached the internal groove in the female portion.
Even though poor locking can lead to the male plug being ejected from the female portion and thus to injuries such as burns, such poor locking of male and female coupling portions one in the other is made all the more likely given that: the molds of an injection molding machine are changed very often; a large number of cooling circuits are needed to obtain very good cooling in the common circumstance of the parts for molding being complex, and/or in the even more common circumstance of high rates of production throughput leading to a large quantity of couplings often being concentrated in a small space; concentrating numerous couplings in a small space reduces accessibility to the couplings; and the hoses are generally coupled to the mold by relatively un-qualified operators.